Description (Applicant Abstract): Lipoxygenases are a family of non-heme iron oxygenases that catalyze the hydroperoxidation of polyunsaturated fatty acids in both animals and plants. In mammals, lipoxygenases products are the precursors of leukotrienes and other biologically active eicosanoids, which play an important role in allergic, immunologic, and inflammatory responses. Soybean lipoxygenase-1 (soylox-1) has been extensively studied as a model for all lipoxygenases. Although in the last 10 years many important structural studies have been done, the molecular details on the mechanism of action of this family of enzymes are still unknown. This research pilot project focuses on the study of the dynamics of soylox-1 in aqueous solution at room temperature, by steady-state fluorescence spectroscopic techniques. The enzyme will be labeled with the thiol-specific fluorescent probes acrylodan and bimane. Fundamental questions such as changes in conformation after binding the substrate, self association between protein units, and residue or subunits displacements during catalysis remain unanswered for this enzyme. The characterization of these properties at physiological conditions is important in order to have a much clearer picture on the role that conformational and dynamical features play in the activity, and biological function of lipoxgenases. With the approach proposed in this project, we will be able to answer the above questions and in this way contribute to the overall understanding of mechanism of action of these biologically relevant enzymes.